Self-centering tubular connection

ABSTRACT

A tubular connection for centering a tube within a female connecting block that has a throughbore with a chamfer, wherein a transition surface is defined between the chamfer and the throughbore. The tube has an upset bead, a tapered portion narrowing from the upset bead, and an end-form extending from the tapered portion, the end-form having an annular groove with an O-ring therein. The connection further includes a device for securing the tube within the female connecting block whereby the upset bead of the tube is caused to abut the female connecting block. The tube locates inside the female connecting block such that the end-form seals via the O-ring inside the throughbore of the female connecting block and the tapered portion of the tube sealingly engages against the transition surface of the female connecting block to keep the tube centered within the female connecting block and to form a secondary fluid-tight seal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tubular connection, and moreparticularly to a tube to block connection incorporating novelself-centering features for more reliability and better fluid-tightsealing in the service life of the connection.

2. Description of the Prior Art

In assembling certain air-conditioning units, such as those used inautomobiles, it is common practice to secure a tube to a femaleconnecting block. In order to effect a fluid-tight seal between the tubeand the female connecting block, an O-ring is situated in an annulargroove in an end-form on the tube. Typically, the end-form of the tubeis initially secured in a male connecting block and then is attached tothe female connecting block by a bolt that extends through an aperturein the male connecting block and threadingly engages the femaleconnecting block. The bolt is located adjacent but spaced away from thetube that in turn engages the female connecting block via a throughboretherein.

The bolt is caused to threadingly engage the female connecting block byapplying a torque in the clockwise direction to the head of the bolt. Inturn, the clockwise torque on the bolt imparts a clockwise torque on themale connecting block causing it to rotate relative to the threads ofthe female connecting block in the clockwise direction. Since the tubeis secured within the male connecting block, the tube likewise pivotsrelative to the threads of the female connecting block in the clockwisedirection. Because the tube is also loosely located within the femaleconnecting block when the torque is applied to the bolt, the tubeundergoes a side-loading phenomenon within the throughbore. That is, thetube and associated O-ring translate within the female connecting blockand become over-compressed on one side and under-compressed on anopposite side. The resultant uneven compression on the O-ring can resultin premature failure of the O-ring at the over-compressed side andleakage of fluid past the O-ring seal at the under-compressed side overthe life of the tubular connection.

Accordingly, there are many examples in the prior art of apparatus toassure proper alignment of tubular connections embodying similar maleand female members. One such example is disclosed in U.S. Pat. No.4,659,116 to Cameron. The Cameron patent discloses a fitting including amale part having a contoured lead end that engages a female end having acomplementary contour. The male and female parts self align as they arejoined together and create a fluid-tight seal. However, the contouredsurfaces of the male and female parts do not prevent off-centercompression of the O-ring once the fitting is clamped together by athreaded collar.

Further, the Cameron patent is representative of the prior art, whichessentially focuses on alignment of male and female members during thejoining process. However, the special problem of aligning a tube withina male-female connecting block connection as described hereinabove isnot addressed in the prior art. The special problem applies to thepresent invention where torque is applied indirectly to the tube duringthe joining process. None of the prior art teaches or suggests apparatusfor centering a tube within a female connecting block and maintainingthe centering during the application of a torque imparted to the tube.

Accordingly, what is needed is a tube to block connection that providesa tube that supports an O-ring, wherein a male connecting blockencircles part of the tube, and the tube can be centered in a borewithin the female connecting block. The tube remains centered during theapplication of a torque to a fastener in the male connecting block. Theresultant centering maintains even compression of the O-ring seal.Moreover, the mating tube and female connecting block can eachaccommodate a greater degree of variation in size and/or shape in eitheror both the tube and female connecting block.

SUMMARY OF THE INVENTION

In accordance with the present invention, the tubular connectionincludes a female connecting block having an end surface, an oppositeend surface, and a throughbore therebetween. The throughbore has achamfer in the end surface such that a transition surface is definedbetween the chamfer and the throughbore. The connection further includesa tube mounted in the throughbore of the female connecting block. Thetube has a tapered portion that engages the transition surface of thefemale connecting block. The tapered portion of the tube terminates inan end-form that has an annular groove with an O-ring therein that formsa primary fluid-tight seal between the tube and the throughbore of thefemale connecting block. A secondary fluid-tight seal is defined by theengagement of the transition surface with the tapered portion of thetube.

According to an alternative configuration, a tapered ring may be usedwhere it is not possible to form the tapered portion on the tube. Here,the tapered ring would encircle the end-form of the tube and replace thetapered portion described above. The tapered ring would function toprovide the requisite interference fit with the transition surface ofthe female connecting block, thereby centering the tube in thethroughbore.

Accordingly, it is an object of the present invention to provide aself-piloting O-ring seal for a tube to block connection that results inno damage to the O-ring during assembly.

It is a further object of this invention to center and constrain thetube within the block so as to prevent lateral movement of the tubewithin the block.

It is yet a further object of this invention to prevent uneven sideloading of the O-ring within the female connecting block due to torquingof the fastener attached to the male connecting block.

These objects and other features, aspects, and advantages of thisinvention will be more apparent after a reading of the followingdetailed description, appended claims, and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional exploded view showing the componentsof the tubular connection of the present invention before completeassembly;

FIG. 2 is a partial cross-sectional view of the tubular connectionhaving the male connecting block and the tube secured to the femaleconnecting block;

FIG. 3 is a partial cross-sectional view taken on the plane indicted byline 3—3 in FIG. 2;

FIG. 4 is a partial cross-sectional exploded view of an alternativeembodiment of the tube shown in FIG. 1; and

FIG. 5 is a partial cross-sectional view similar to FIG. 4 but shows themale connecting block and tube secured to the female connecting block.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In describing the preferred embodiment of the present invention,reference is made to the drawings, wherein there is seen in FIG. 1 theunassembled components of a tubular connection 10. The tubularconnection 10 includes a tube 20, a female connecting block 40, a maleconnecting block 60, and a bolt 80.

The tube 20 is best seen in FIG. 1 and includes an upset bead 22 and apair of annular grooves 24 on the outside diameter thereof. A pair ofO-rings 26 are seated in the annular grooves 24. The tube 20 includes atapered portion 28 that narrows from the upset bead 22, terminating inan end-form 30 of the tube 20. Details of the tapered portion 28 arefurther discussed herein below.

The second component of the tubular connection 10 is the femaleconnecting block 40 that includes an end or top surface 42, an oppositeend, or bottom surface 44, and a throughbore 46 therebetween. Thethroughbore 46 includes a chamfer 48 in the top surface 42. An annularedge or transition surface 50 is defined at the intersection of thechamfer 48 and the throughbore 46. The female connecting block 40 alsoincludes a threaded hole 52 adjacent but spaced from the throughbore 46.Details of the chamfer 48 are further discussed hereinbelow.

The third component of the tubular connection 10 is the male connectingblock 60 that includes a throughbore 62 and a counterbore 64 in a matingsurface 63 that intersect and are coaxial. The diameter of thecounterbore 64 is greater than the diameter of the throughbore 62. Thedifferent size diameters of the throughbore 62 and counterbore 64 definea shoulder 66. As best seen in FIGS. 1 and 2, the diameter of thethroughbore 62 is slightly greater than an outer diameter “e” of thetube 20. Similarly, the counterbore 64 is slightly greater in diameterthan the diameter of the upset bead 22. The male connecting block 60additionally includes a bolthole 68.

The fourth and final component of the tubular connection 10 is the bolt80, which is conventional and includes a threaded shank 82 and ahexagonal head 84. The threaded shank 82 is smaller in diameter than thebolthole 68 of the male connecting block 60.

As best seen in FIG. 1, the chamfer 48 of the female connecting block isoriented at an acute angle “a” to the axis of the throughbore 46 of thefemale connecting block 40. Likewise, the tapered portion 28 of the tube20 is oriented at an acute angle “b” to the axis of the end-form 30 ofthe tube 20. The acute angles “a” and “b” can vary, but it is preferablethat angle “a” be greater than angle “b”. However, should angle “a” beless than angle “b”, the invention would still work. Instead, thetapered portion 28 would engage the female connecting block 40 where thechamfer 48 intersects the top surface 42. Also, the tapered portion 28of the tube 20 has an axial length “x” and the chamfer 48 has an axiallength “y”. Preferably, the length “x” should always be at least equalto the length “y” and more preferably, the length “x” should exceed thelength “y”. As above, however, should length “x” be less than length“y”, the invention will still work. Further, the throughbore 46 of thefemale connecting block 40 has a diameter “d” that is intermediate adiameter “f” of the tapered portion 28 and the outer diameter “e” of theend-form 30.

The key objective in aligning the tube 20 in the female connecting block40 is to avoid uneven compression of the O-rings 26 during the assemblyprocess. The first stage of the assembly process includes placing thetube 20 within the female connecting block 40. In so doing, the chamfer48 acts as a guide in order that the tube 20 may be centered within thethroughbore 46. The upset bead 22 is caused to mount flush against thetop surface 42 of the female connecting block 40 and the tapered portion28 of the tube 20 is caused to pilot and center about the transitionsurface 50 of the female connecting block 40.

As seen in FIG. 2, the guiding action of the chamfer 48 allows theO-rings 26 to attain the positions without the O-rings 26 undergoinguneven compression due to side-loading from torquing of the bolt 80.Therefore, the O-rings 26 circumferentially engage the throughbore 46 todefine a primary fluid-tight seal. Additionally, the transition surface50 sealingly engages the tapered portion 28 by circumferentiallypenetrating its surface to define a secondary fluid-tight seal.

Referring again to FIG. 1, assembly of the tubular connection 10 furtherinvolves placing the male connecting block 60 over a free end 32 of thetube 20 before the upset bead 22 is formed on the tube. Then the upsetbead 22 is formed on the tube and within the counterbore 64 of the maleconnecting block 60, by an axial upsetting process, as is well known inthe art. The male connecting block 60 and the tube 20 are then advancedtoward the top surface 42 of the female connecting block 40. Theend-form 30 of the tube 20 is inserted into the throughbore 46 of thefemale connecting block 40. The upset bead 22 locates flat against thetop surface 42 of the female connecting block 40, and the taperedportion 28 of the tube 20 engages the transition surface 50 of thefemale connecting block 40. Ultimately, the O-rings 26 form a primaryfluid-tight seal between the tube 20 and the throughbore 46 of thefemale connecting block 40.

Referring now to FIG. 2, the final stage of assembly of the tubularconnection 10 includes placing the threaded shank 82 of the bolt 80through the bolt hole 68 of the male connecting block 60 and into thethreaded hole 52 of the female connecting block 40. A clockwise torqueis then applied to the hexagonal head 84 of the bolt 80 that causes thebolt 80 to threadingly engage the threaded hole 52 of the femaleconnecting block 40. The engagement of the threaded hole 52 by the bolt80 effects a locking arrangement between the male connecting block 60and the female connecting block 40.

Consequently, the application of the clockwise torque to the bolt 80ordinarily would cause the male connecting block 60 to rotate a veryslight amount about the throughbore 46 in the clockwise direction, asindicated by the arrows in FIG. 3. However, such rotation is resistedusing the present invention because the tapered portion 28 pilots andthereby maintains the tube 20 centered within the throughbore 46 of thefemale connecting block 40. This resistance to rotation amounts to anabsence of lateral movement of the tube 20 within the female connectingblock 40 and prevents uneven compression of the O-rings 26. The absenceof uneven compression of the O-rings 26 substantially reduces theincidence of premature failure in the O-rings 26 and resultant leakageof fluid past the O-rings 26.

In the foregoing preferred embodiment illustrated in FIGS. 1 through 3,the tube 20 was formed to include the tapered portion 28 in order toprevent movement of the tube 20 after being inserted into the femaleconnecting block 40. The same result can be achieved without the tube 20being formed to include the tapered portion 28 as shown in FIG. 4.There, a tubular connection 10′ is an alternative embodiment of thetubular connection 10 seen in FIGS. 1 through 3. The only difference inthe alternative connection 10′ is that a tube 20′ lacks the taperedportion 28 of FIGS. 1 through 3. The functionality of the taperedportion 28 in the tube 20 of FIGS. 1 through 3 is attained here by theuse of a plastic or soft metal tapered ring 21′ that initially is placedon the tube 20′ encircling an end-form 30′ and adjacent an upset bead22′. The end-form 30′ has a pair of annular grooves 24′ that hold thepair of O-rings 26.

Referring now to both FIGS. 4 and 5, the tapered ring 21′ includes atapered portion 28′ that is analogous to the tapered portion 28 of thetube 20 of FIGS. 1 through 3. The tapered portion 28′ bears the samerelationship in terms of angles and distances to the female connectingblock 40 of FIGS. 4 and 5, as does the tapered portion 28 of the tube 20with respect to the female connecting block 40 of FIGS. 1 through 3.When the tube 20′ is located within the female connecting block 40, thetapered ring 21′ seats against the transition surface 50 of the femaleconnecting block 40 to keep the tube 20′ centered therein.

Accordingly, an advantage of the present invention is that the tubeself-aligns to the female connecting block during assembly, therebyreducing the risk of damaging the O-rings. This self-aligning actionalso constrains and centers the tube within the female connecting blocksuch that the tube is prevented from moving laterally within the femaleconnecting block from the torque that is applied to the mounting bolt.Preventing lateral movement of the tube prevents side loading theO-rings and leads to more equally distributed compressive loads upon theO-rings within the throughbore of the female connecting block. Testsconducted by the applicant reveal that this technology may result in 35%more squeeze at minimum material condition and may lead to a reductionin the tolerance stack-up for the tubular connection of 4%.

An additional advantage is that the sealing potential of the connectionis improved. The transition surface of the female connecting blockcircumferentially penetrates into the tapered portion of the tube so asto form a secondary fluid-tight seal thus further preventing fluid fromleaking from the connection. Finally, this technology will enable use ofpower tools to torque the tubular connection at higher torque withoutrisk of side loading the O-rings.

From the foregoing description, it should be understood that variouschanges can be made in the above constructions without departing fromthe scope of the invention. It is intended that all matter contained inthe above description or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense. For example,the tube need not include the upset bead, and may be secured to thefemale connecting block in any other conventional fashion.

1. A tubular connection, comprising: a female connecting block having anend surface, an opposite end surface, and a throughbore therebetween,said throughbore having a chamfer in said end surface, said chamfer andsaid throughbore intersect to define an annular edge; and a tube mountedin said throughbore of said female connecting block, said tube having atapered portion in contact with said annular edge of said femaleconnecting block, said tapered portion being seated against said annularedge and terminating in an end-form, said end-form having at least oneannular groove for receiving at least one seal member therein, said atleast one seal member forming a primary fluid-tight seal between saidtube and said female connecting block.
 2. The tubular connection ofclaim 1, wherein said tube further has an upset bead thereon, saidtapered portion being positioned between said end-form and said upsetbead, said upset bead abutting said end surface of said femaleconnecting block.
 3. The tubular connection of claim 1, furthercomprising: means for securing said tube within said throughbore of saidfemale connecting block, said securing means mounted to said end surfaceof said female connecting block.
 4. The tubular connection of claim 3,wherein said securing means includes a male connecting blockcircumscribing said tube.
 5. The tubular connection of claim 1, whereinsaid annular edge of said female connecting block sealingly engages thecircumference of said tapered portion of said tube to define a secondaryfluid-tight seal between said tube and said female connecting block. 6.A tubular connection, comprising: a female connecting block having anend surface, an opposite end surface, and a throughbore therebetween,said throughbore having a chamfer in said end surface, said chamfer andsaid throughbore intersecting to define a transition surface; and a tubemounted in said throughbore of said female connecting block, said tubeterminating in an end-form, said tube further comprising a tapered ringcircumscribing said end-form and having a tapered portion thereon, saidtapered portion being seated against said transition surface of saidfemale connecting block, said end-form having at least one annulargroove for receiving at least one seal member therein, said at least oneseal member forming a primary fluid-tight seal between said tube andsaid female connecting block.
 7. The tubular connection of claim 6,wherein the axial length of said tapered ring is greater than the axiallength of said chamfer of said female connecting block.
 8. The tubularconnection of claim 7, wherein said chamfer is oriented at an acuteangle “a” to the longitudinal axis of said throughbore of said femaleconnecting block, and said tapered portion of said tapered ring isoriented at an acute angle “b” to the longitudinal axis of said end-formof said tube, and further wherein said angle “a” is greater than saidangle “b”.
 9. The tubular connection of claim 8, wherein saidthroughbore is greater in diameter than said end-form of said tube butlesser in diameter than said tapered portion of said tapered ring. 10.The tubular connection of claim 6, wherein said transition surface ofsaid female connecting block sealingly engages the circumference of saidtapered portion of said tapered ring to define a secondary fluid-tightseal between said tube and said female connecting block.